Absorbent article containing structured fibers

ABSTRACT

A reusable absorbent article includes a hydrophilic top layer, a soaking layer adjacent to and beneath the top layer, a substantially liquid impermeable layer adjacent to and beneath the soaking layer, and a backing layer adjacent to and beneath the substantially liquid impermeable layer. All of the layers are secured together to form a unitary structure. The soaking layer is a non-woven fabric having a plurality of hydrophobic fibers of a generally circular cross-sectional shape and a plurality of hydrophilic fibers of a non-circular cross-sectional shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/231,114, filed on Aug. 4, 2009, entitled “Underpad,” the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

Persons who are elderly, handicapped, seriously injured or ill often face difficulties in performing the most common of daily activities, particularly if they are immobile or confined to their beds. As such, several products have been developed for and are used by these persons in their homes, hospitals or short- or long-term care facilities. Incontinence underpads, for example, are often used by medical professionals in caring for patients who cannot easily move around or are completely confined to their beds. Underpads acts as moisture barriers to protect surfaces, such as bedding, on which the user is resting, from damage caused by moisture voluntarily or involuntarily released by the user. Additionally, such underpads serve to enhance the comfort of the user or patient by absorbing such moisture so that the user is kept relatively dry. Reusable underpads, in particular, are also environmentally friendly because they need not be disposed of after each use, but rather can be laundered and used again.

Conventional reusable underpads have a multi-layered structure, wherein the top layer comprises a fabric made of a polyester and cotton blend and is quilted to an adjacent absorbent layer. Such underpads generally also have a vinyl barrier forming the bottom layer of the structure. However, such conventional reusable underpads are generally inferior for a number of reasons. For example, their typical construction cannot withstand a great number of launderings, particularly institutional or industrial launderings, without deteriorating. Further, they are often made of materials which do not absorb and disperse moisture effectively, such that the surface of the underpad in contact with the user or patient can often remain wet for a significant amount of time, which leads to the user or patient being uncomfortable.

It would therefore be beneficial to provide a reusable underpad which is resilient and which effectively absorbs and disperses moisture effectively to maximize the comfort of the user.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, an embodiment of the present invention is directed to a reusable absorbent article including a hydrophilic top layer, a soaking layer adjacent, to and beneath the top layer, a substantially liquid impermeable layer adjacent to and beneath the soaking layer, and a backing layer adjacent to and beneath the substantially liquid impermeable layer. All of the layers are secured together to form a unitary structure. The soaking layer is a non-woven fabric having a plurality of hydrophobic fibers of a generally circular cross-sectional shape and a plurality of hydrophilic fibers of a non-circular cross-sectional shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings an embodiment which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the Drawings:

FIG. 1 is a top plan view of an underpad according to a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional side elevational view of the underpad shown in FIG. 1; and

FIG. 3 is a cross-sectional view of a fiber of a layer of the underpad shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower” and “upper” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the underpad and designated parts thereof. Unless specifically set forth herein, the terms “a”, “an” and “the” are not limited to one element but instead should be read as meaning “at least one”. The terminology includes the words noted above, derivatives thereof and words of similar import.

Referring to the drawings in detail, wherein like numerals and characters indicate like elements throughout, there are shown in FIGS. 1-2 a presently preferred embodiment of an underpad in accordance with the present invention. With reference initially to FIGS. 1-2, the underpad 10, includes a top layer 12 and a bottom layer 18.

With particular reference to FIGS. 1-2, the underpad 10 serves as a reusable and launderable incontinence pad and comprises a plurality of layers and, in particular, four layers. The first or top layer 12 is made of a hydrophilic material or of a material that has been subjected to a hydrophilic treatment. As such, the hydrophilic top layer 12 has a strong affinity for water and other fluids and, thus, readily absorbs moisture. A first or top surface 12 a of the top layer 12 is in contact with the body of the user. The material of the top layer 12 is preferably a polyester brushed fabric, thereby providing a soft and comfortable surface in contact with the body of the user. However, it will be understood by those skilled in the art that any material having similar properties to a polyester brushed fabric may be used.

A second or intermediate absorbent layer 14 is disposed adjacent to and beneath or below the top layer 12. In particular, a top surface 14 a of the second layer 14 is directly in contact with a second or bottom surface 12 b of the top layer 12. The second layer 14 is an absorbent layer 14 that functions as a distribution or soaking layer 14, for absorption, containment and distribution of liquid. The soaking layer 14 has a thickness of approximately 2.5-3.0 millimeters, and a mass per unit area of 350 grams per square meter.

The soaking layer 14 is preferably made of a non-woven needle punch fabric and comprises a plurality of hydrophobic fibers and a plurality of hydrophilic fibers. The hydrophobic fibers are preferably polyester fibers and have a generally circular cross-sectional shape. The hydrophilic fibers, on the other hand, are shaped fibers, meaning they have a non-circular cross-sectional shape, and are preferably made of a polyester resin. The hydrophilic shaped fibers have a denier of approximately 3.0 and, more preferably, of 2.78, a length of approximately 3-5 centimeters and a diameter of approximately 4-5 microns. Preferably, the soaking layer 14 comprises approximately 60-65% polyester hydrophobic fibers and 35-40% hydrophilic fibers.

The hydrophilic shaped fibers facilitate the absorption of moisture away from the top layer 12 and dispersion of the absorbed moisture throughout the soaking layer 14 and, more particularly, toward a bottom surface 14 b of the soaking layer 14. The hydrophobic polyester fibers facilitate containment of the absorbed moisture within the soaking layer 14. More specifically, the absorbed moisture is contained within the hydrophilic shaped fibers and between the hydrophobic polyester fibers.

The hydrophilic shaped fibers have a unique cross-section, as shown in FIG. 3, which enables them to absorb and disperse moisture quickly. Specifically, each hydrophilic shaped fiber 22 has a substantially “x”-shaped cross section. The notches 24 formed by the cross sectional shape of the fibers 22 create a siphoning effect to draw moisture away from the top layer 12 and to facilitate the movement of the absorbed moisture along the length of the fibers 22 and toward the bottom surface 14 b of the soaking layer 14.

The hydrophilic shaped fibers 22 of the soaking layer 14 are quick-drying fibers and have a vertical wicking rate of approximately 5.7 millimeters per minute, significantly faster than that of cotton (3.3 millimeters per minute) and of nylon (1.7 millimeters per minute). Also, the hydrophilic shaped fibers 22 of the soaking layer 14 have a diffusion area of approximately 74.7 square millimeters per second, significantly larger than that of cotton (50 square millimeters per second) and of nylon (11.7 square millimeters per second).

Thus, because the soaking layer 14 comprises a combination of the shaped hydrophilic fibers 22 and circular hydrophobic fibers, the soaking layer 14 is formed of a breathable material which draws moisture away from the top layer 12 and the user's body and quickly absorbs and disperses the moisture. In particular, the absorbed moisture is quickly dispersed toward the bottom surface 14 b of the soaking layer 14 and is contained within the soaking layer 14. Consequently, the top surface 12 a of the top layer 12 quickly becomes dry after it is subjected to a release of moisture, thereby enhancing the comfort and dryness of the user.

Many conventional underpads utilize a polyester/rayon blend as the material of the soaking layer, where both fibers are of a circular cross-sectional shape. However, such fibers cannot absorb and disperse moisture as quickly as the shaped hydrophilic fibers. This is why the top surface of conventional underpads does not dry as quickly as the top surface 12 a of the underpad 10.

A third layer 16 is disposed adjacent to and beneath or below the soaking layer 14, and is directly in contact with the bottom surface 14 b of the soaking layer 14. The third layer 16 functions as a barrier layer which is substantially impermeable to liquid. The barrier layer 16 is preferably made of a high temperature resistant polymer film, such as a polyurethane film, which is a breathable and waterproof material. As such, the barrier layer 16 prevents absorbed moisture within the soaking layer 14 from passing therethrough. It will be understood by those skilled in the art that while a polyurethane film is described, the barrier layer 16 may comprise any polymer film having similar or equivalent properties to polyurethane. The barrier layer 16 has a thickness of approximately 25 to 30 micrometers and is attached to the fourth or bottom backing layer 18. Accordingly, the backing layer 18 is disposed adjacent to and beneath or below the barrier layer 16, and is in contact with the surface on which the user is resting, sitting, lying, etc. The bottom layer 18 is preferably made of a substantially liquid impermeable material that provides a non-slip surface between the underpad 10 and the surface on which the user is resting, sitting, lying, etc. Preferably, the bottom layer 18 is made of a polyester tricot fabric.

One or more of the layers 12, 14, 16, 18 of the underpad 10 may be secured or attached to each other by conventional means, such as by quilting, lamination, heat sealing, or with liquid adhesives. Preferably, the barrier layer 16 is laminated to the bottom layer 18. Preferably, once the layers 12, 14, 16, 18 are assembled and secured or attached to each other, a border 20 is provided to cover the edges of the layers 12, 14, 16, 18. The edges 10 a of the underpad 10, covered by the border 20, are stitched together at a seam 11. The border 20 serves to keep the layers 12, 14, 16, 18 attached together, such that the layers 12, 14, 16, 18 form a unitary structure, and enhances the visual appearance of the underpad 10.

Because of the unique composition of the soaking layer 14, the underpad 10 has superior absorption properties and provides for maximum comfort of the user by keeping the user dry. In particular, the underpad 10 has a fluid holding capacity of approximately 2 liters per square meter and can hold a total of 1.6 liters of fluid. The underpad 10 also has an average surface wicking percentage of approximately 3% or less. In addition; the underpad 10 has an average speed of absorption of approximately 3 milliliters per second and an average speed of spread of the moisture of approximately 0.9 milliliters per second.

Further, all of the aforementioned materials used to form each layer 12, 14, 16, 18 of the underpad 10 have a superior ability to be processed (i.e., laundered) institutionally, thereby resulting in an underpad 10 that is durable and capable of withstanding several hundred launderings without suffering any significant changes or deterioration. The resilience of the underpad 10 is best demonstrated by a comparison of various properties and dimensions of the underpad 10 prior to and after laundering.

When it is initially manufactured, a preferred embodiment of the underpad 10 has a standard length of approximately 855 millimeters and an average length of approximately 860 millimeters. The underpad 10 has a standard width of approximately 912 millimeters and an average width of approximately 910 millimeters. The absorbent area of the underpad 10 is of a dimension of approximately 0.7 square meters and has a total mass of approximately 551 grams. The overall mass per unit area of the underpad 10 is 706 grams per square meters. The underpad 10 may be of any other suitable size, depending on the application for which it will be used.

Experiment 1

The underpad 10 was subjected to five launderings and various dimensions and properties of the laundered underpad 10 were measured. Notably, there was less than 5% shrinkage of the underpad 10. Specifically, after five launderings, the average length of the underpad 10 was 834 millimeters, a change of only about 2.4%, and the average width was 905 millimeters, a change of only about 0.8%. Further, the mass per unit area of the underpad 10 only changed slightly, to about 727 grams per square meter. Thus, the underpad 10 is clearly resilient and does not undergo significant changes in dimension when processed institutionally.

Further, after five launderings, the underpad 10 still had a fluid absorption capacity of 2 liters per square meter and an average surface wicking percentage of approximately 1.4%. The underpad 10 also had an average speed of absorption of approximately 3.2 milliliters per second and an average speed of spread of approximately 2.9 milliliters per second. Thus, the absorption capabilities of the underpad 10 remain superior and effective even after laundering.

COMPARATIVE EXAMPLE 1

In order to further test the absorption properties of the underpad 10, 350 grams of water were applied to the underpad 10 and to a prior art known underpad. After three minutes, the top surfaces of both underpads were touched and observed. The top surface 12 a of the underpad 10 was completely dry, while that of the prior art known underpad was still wet. Thus, the underpad 10 is clearly a quick-drying underpad and has superior absorption capabilities as compared with conventional underpads.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

We claim:
 1. A reusable absorbent article comprising: an outer surface having hydrophilic top layer; a soaking layer adjacent to and beneath the top layer, the soaking layer being secured to and distinct from the top layer; a substantially liquid impermeable layer adjacent to and beneath the soaking layer; and a backing layer adjacent to and beneath the substantially liquid impermeable layer, all of the layers being secured together to form a unitary structure, wherein the soaking layer is a non-woven needle punch fabric comprising 60% -65% hydrophobic polyester fibers of a generally circular cross-sectional shape and 35% -40% hydrophilic polyester resin fibers of a non-circular cross-sectional shape.
 2. The reusable absorbent article of claim 1, wherein the hydrophilic fibers of the soaking layer have a substantially X-shaped cross-section.
 3. The reusable absorbent article of claim 1, wherein the hydrophilic fibers of the soaking layer have a denier of approximately 3.0 and a fiber length in the range of from 3-5 cm.
 4. The reusable absorbent article of claim 1, wherein the top layer is comprised of a polyester brushed fabric.
 5. The reusable absorbent article of claim 4, wherein the top layer is comprised of a hydrophilic material.
 6. The reusable absorbent article of claim 4, wherein the top layer is comprised of a material which has been subjected to a hydrophilic treatment.
 7. The reusable absorbent article of claim 1, wherein the substantially liquid impermeable layer is a polymeric film.
 8. The reusable absorbent article of claim 7, wherein the substantially liquid impermeable layer is a polyurethane film.
 9. The reusable absorbent article of claim 1, wherein the backing layer is comprised of a polyester tricot fabric and has at least one substantially non-slip surface.
 10. The reusable absorbent article of claim 1, wherein the substantially liquid impermeable layer is laminated to the backing layer.
 11. The reusable absorbent article of claim 1, wherein the top layer, the soaking layer, the substantially liquid impermeable layer and the backing layer are secured to each other at a stitched seam.
 12. The reusable absorbent article of claim 1 having a fluid holding capacity of approximately 2 L/m².
 13. The reusable absorbent article of claim 1, wherein the reusable absorbent article is launderable.
 14. A reusable absorbent article comprising: an outer surface having a hydrophilic top layer comprising a polyester brushed fabric; a soaking layer adjacent to and beneath the top layer, the soaking layer being secured to and distinct from the top layer, the soaking layer being a non-woven needle punch fabric comprising a plurality of hydrophobic polyester fibers of a generally circular cross-sectional shape and a plurality of hydrophilic polyester resin fibers of a substantially X-shaped cross-section; a substantially liquid impermeable polyurethane film adjacent to and beneath the soaking layer, and a polyester tricot fabric backing layer adjacent to and beneath the substantially liquid impermeable layer, all of the layers being secured together to form a unitary structure.
 15. The reusable absorbent article of claim 14, wherein the hydrophilic polyester resin fibers of the soaking layer have a denier of approximately 3.0 and a fiber length in the range of from 3-5 cm.
 16. The reusable absorbent article of claim 14 having a fluid holding capacity of approximately 2 L/m². 